Measurement of the velocity of a flowing gas or air stream within a duct is commonly made with a Pitot tube or an inclined manometer. Unfortunately, a Pitot tube is not a directionally sensitive device and thus it is very difficult to determine whether the probe is properly oriented in the stream. Improper orientation usually results in inaccurate measurements of velocity pressure or the square root thereof, which is representative of velocity. Proper orientation of the probe with respect to the flowing gas or air stream is required in order to obtain accurate measurements of the foregoing parameters. The use of an inclined manometer also has several inherent disadvantages in that it usually requires a steady surface for supporting same and the operator thereof needs a fairly high degree of experience in order to develop an ability to determine an average value from the velocity pressure readings that are taken.
Because of the foregoing, it has now become desirable to develop a portable device which can accurately measure the velocity pressure or the square root of velocity pressure of a flowing gas or air stream, average these readings, and display same to the operator thereof.